Autism spectrum disorders can be diagnosed through IQ tests with brain imaging to rule out lesions, questionnaires / interviewing, or a combination of both. An IQ test showing a large discrepancy between verbal and visual IQ is a big sign of being on the autistic spectrum, if there is no sign of brain damage. The questionnaires tend to look an awful lot like this one although with developmental history also taken into consideration. I think that this test is good for basic screening for Autism. One research paper claimed that scoring below 26 definitely rules out a diagnosis of Aspergers. However the test is not meant to be diagnostic. On the other hand, when this test was being evaluated, only 2% of neurotypical people scored 32 or higher. So I think scoring 32 or higher strongly indicates Autism, and scoring 26 or higher indicates a possibility of Aspergers.